Description

In the Linux kernel, the following vulnerability has been resolved:

ipv4: ip_tunnel: Fix suspicious RCU usage warning in ip_tunnel_find()

The per-netns IP tunnel hash table is protected by the RTNL mutex and
ip_tunnel_find() is only called from the control path where the mutex is
taken.

Add a lockdep expression to hlist_for_each_entry_rcu() in
ip_tunnel_find() in order to validate that the mutex is held and to
silence the suspicious RCU usage warning [1].

[1]
WARNING: suspicious RCU usage
6.12.0-rc3-custom-gd95d9a31aceb #139 Not tainted
-----------------------------
net/ipv4/ip_tunnel.c:221 RCU-list traversed in non-reader section!!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
1 lock held by ip/362:
#0: ffffffff86fc7cb0 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x377/0xf60

stack backtrace:
CPU: 12 UID: 0 PID: 362 Comm: ip Not tainted 6.12.0-rc3-custom-gd95d9a31aceb #139
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
Call Trace:

dump_stack_lvl+0xba/0x110
lockdep_rcu_suspicious.cold+0x4f/0xd6
ip_tunnel_find+0x435/0x4d0
ip_tunnel_newlink+0x517/0x7a0
ipgre_newlink+0x14c/0x170
__rtnl_newlink+0x1173/0x19c0
rtnl_newlink+0x6c/0xa0
rtnetlink_rcv_msg+0x3cc/0xf60
netlink_rcv_skb+0x171/0x450
netlink_unicast+0x539/0x7f0
netlink_sendmsg+0x8c1/0xd80
____sys_sendmsg+0x8f9/0xc20
___sys_sendmsg+0x197/0x1e0
__sys_sendmsg+0x122/0x1f0
do_syscall_64+0xbb/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Classification

CVE ID: CVE-2024-50304

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.0% (scored less or equal to compared to others)

EPSS Date: 2025-03-03 (when was this score calculated)

References

https://git.kernel.org/stable/c/31bd7378c6fe100a8af0e996ea0b5dafd3579df6
https://git.kernel.org/stable/c/6ac5dfa575136da8dd8a9e7c1437c41f3a593993
https://git.kernel.org/stable/c/ce11424026cbf87d5861b09e5e33565ff7f2ec8d
https://git.kernel.org/stable/c/e0500e4373cd3d5eace1f1712444ab830b82c114
https://git.kernel.org/stable/c/f20fe2cfe06ca1b008b09da4f2b4e0c5547ccef6
https://git.kernel.org/stable/c/90e0569dd3d32f4f4d2ca691d3fa5a8a14a13c12

Timeline